Olhei para o retrovisor e liguei os piscas antes de mudar de faixa.

Olhei is the 1st person singular of the verb olhar in the pretérito perfeito (the simple past).

So:

• olhar = to look
• olhei = I looked

This tense is used because the sentence describes completed actions in the past:

• Olhei para o retrovisor
• liguei os piscas

A native English speaker might think of it as I looked and I turned on.

Portuguese often leaves out the subject pronoun when the verb form already makes it clear who is doing the action.

Here:

• olhei already means I looked
• liguei already means I turned on

So eu is not necessary.

You could say:

• Eu olhei para o retrovisor...

but it is usually omitted unless you want emphasis or contrast.

With olhar, Portuguese very often uses para when you mean to look at something.

So:

• olhar para = to look at

Examples:

• Olhei para a estrada. = I looked at the road.
• Ela olhou para mim. = She looked at me.

For learners, it is best to remember olhar para as a set pattern.

Retrovisor means a rear-view mirror or mirror used to see behind you.

In driving contexts, it can refer to:

• the interior rear-view mirror
• sometimes a side mirror, depending on context

If the sentence just says o retrovisor, it usually means the mirror relevant in that moment. The exact mirror may be clear from context.

In European Portuguese, os piscas is a very common way to refer to the car’s indicators / turn signals / blinkers.

Literally, piscar means to blink, so piscas are the lights that blink.

• ligar os piscas = to turn on the indicators

This is very natural in Portugal.

You may also hear more formal wording such as:

• os indicadores de mudança de direção

But in everyday speech, os piscas is much more common.

It is commonly used in the plural in Portuguese when referring to the turn indicators as a system.

So even if in practice you are signaling only one direction, Portuguese often says:

• ligar os piscas

This is just the normal idiomatic expression.

Similar everyday patterns exist in many languages where the grammatical form does not match a strict one-item idea.

Yes, ligar can literally mean to connect, but in everyday Portuguese it also means to turn on / switch on devices, lights, engines, etc.

So here:

• liguei os piscas = I turned on the indicators

Other examples:

• Liguei a luz. = I turned on the light.
• Ligaram o motor. = They started the engine.

This is a very common verb in Portuguese.

After antes de, Portuguese uses the infinitive.

So:

• antes de mudar = before changing

This structure is very common:

• antes de sair = before leaving
• antes de comer = before eating
• antes de falar = before speaking

So antes de + infinitive is the pattern to remember.

In Portuguese, the idea of changing lanes is expressed as:

• mudar de faixa

Here, de is part of the normal expression. It links mudar to the new lane/track category in an idiomatic way.

So you should learn it as a chunk:

• mudar de faixa = to change lanes

Other similar expressions also use de after mudar, depending on meaning, for example:

• mudar de assunto = to change the subject
• mudar de roupa = to change clothes

In this sentence, faixa means a traffic lane.

Be careful, because faixa has several meanings in Portuguese depending on context, such as:

• stripe
• band
• belt/sash
• lane

In driving, faixa often means lane, especially in the expression:

• mudar de faixa = to change lanes

Not in this sentence.

Here, after antes de, you need the infinitive:

• antes de mudar de faixa = before changing lanes

If you said antes de mudei de faixa, that would be grammatically wrong.

Compare:

• Mudei de faixa. = I changed lanes.
• Antes de mudar de faixa... = Before changing lanes...

So:

• mudei = past tense, finite verb
• mudar = infinitive

Because the sentence tells a sequence of completed actions in the past.

The structure is:

1. Olhei para o retrovisor
2. e liguei os piscas
3. antes de mudar de faixa

So the speaker is narrating what they did.

Portuguese often uses the pretérito perfeito for this kind of completed action sequence, just like English uses the simple past:

• I looked
• I turned on
• before changing

Yes. The sentence suggests a logical sequence:

1. I looked at the mirror
2. I turned on the indicators
3. before changing lanes

The phrase antes de mudar de faixa applies to the earlier actions and shows they happened before the lane change.

So it communicates safe driving order.

Yes. In this sentence, e is just the normal conjunction and:

• Olhei para o retrovisor e liguei os piscas...
• I looked at the mirror and turned on the indicators...

It links the two past actions.

Yes, it sounds very natural in Portugal, especially because of os piscas.

A Brazilian learner would understand it, but some word choices may differ by region. For example, vocabulary for driving can vary.

For Portuguese (Portugal), this sentence is very idiomatic and natural.

In European Portuguese, connected speech often reduces unstressed vowels.

So os piscas may sound closer to:

• ush piscas or even sh piscas in fast speech

This happens because os is unstressed and the final s before another consonant can sound like sh.

You do not need to spell it differently; this is just a pronunciation point that helps with listening comprehension.